Shouldn't it only affect passive mobs/animals? I can't imagine zombies getting scared off by the horn.

also villages should want to get off the track if they are on it no matter what

As someone who spent 9 years working on the rails, I disagree with villies avoiding the rails. Every single day, we would see people walking the tracks. I know this may be complex and outside the scope of what is reasonable, but in my opinion, blowing the horn should have around a 90-95% chance of causing villies to leave the tracks. IRL, some don't pay any attention (either lost in their own world or the grimmer alternative for them not moving). A 5-10% chance of them staying on the tracks and getting ran over would be closer to realistic. Really this should apply to villies and passive mobs. Hostile mobs I agree with WrongWeekend. They would be like bandits and stay right there

heh, I like that